472 Happon— The Actiniaria of Torres Straits. 
Sphincter muscle,—The sphincter muscle (Pl. xxxt., fig. 1.) of this species is 
very small compared with the size of the polyp; it consists of several long, thin, 
slightly branched plaits of the mesoglea (PI. xxxt., fig. 2); but in some sections 
two of the distal plaits are very much larger than the others, and are richly 
branched (PI. xxxt., fig. 3), and here we have an approach to a circumscribed 
sphincter. The latter figure also shows a section of a sucker. The endoderm 
contains numerous zooxanthelle. 
Radianthus Malu (H. & S$.) 
Discosoma Malu, . . . Wadd. and Shackl. 1893; Proc. R. D. 8. vu, p. 120. 
(RE XV), fies 32 5 PS XexeXy ates eee on) 
Form.—Column, soft, massive; upper portion with a broad zone of large, 
fairly widely separated suckers, to which pieces of shell often adhere; a slight 
but distinct crenulated parapet; oral disk of much greater diameter than column, 
and thrown into folds; mouth round, with two well-marked gonidial grooves ; 
tentacles very numerous, contractile, may be reduced to mere filaments; the 
marginal tentacles are in two cycles, large, and of the same size; the accessory 
tentacles appear to arise anywhere on the disk, they usually occur in short radial 
rows, of these the tentacle situated nearest to the mouth is the largest. 
Colour.—Whole body pale creamy yellow; the tentacles shade off into pink, 
and have rosy-red tips. 
Dimensions.—Column about 100 mm. (4 in.) high; about 75 mm. in diameter ; 
diameter of corona over 160mm.; length of tentacles 22 mm. 
Habitat.—(Of single specimen) surface of reef, Mer. 
Sphincter muscle.—Still less conspicuous than in the last species is the sphincter 
of this species (Pl. xxxt., fig. 4). It consists of a number of fine, and often many 
branched plaits of the mesoglea; distally there is a relatively great branch of 
these; their appearance is shown in detail in Pl. xxx., fig. 5. The sphincter 
sometimes appears to be lodged within two of the folds of the branched meso- 
gleeal plaitings that characterise the body-wall of this species. 
STOICHACTIS, n.g. 
Discosomide usually of large size; column smooth below, and with verrucze 
above. ‘Tentacles vary in form from moderately short and subulate, to short and 
blunt, and even to quite small and capitate. Two gonidial grooves. Sphincter 
muscle strong and circumscribed. I think it is desirable to erect a new genus 
